Fasteners are hardware devices for mechanically joining two or more objects together. A huge variety of fasteners exist, wherein depending on their application, fasteners can occur as individual parts or as assemblies of multiple parts. A nut is a type of such a part, which comprises a threaded hole and is used together with a mating bolt for fastening e.g. a stack of layers together. Commonly, such nut fasteners are used together with washers, which serve for distributing the compressive force generated by the fastener e.g. on the layers.
Such fasteners can e.g. be applied for assembling bus bars together. Bus bars are used for electrical power distribution in switchboards and distribution boards or whenever high current is transmitted from generators or transformers to electrical apparatuses, e.g. to electrical vehicles, charging stations, or wind turbines.
Joining bus bars together demands for fasteners, which are not only unsusceptible to temperature variations, due to the high temperatures they might be exposed to, but also can be fastened in a way, such that the bus bars themselves are not harmed. Therefore, the nuts of such a connection are commonly assembled together with a flat washer and a disc-spring as demonstrated in document U.S. Pat. No. 5,941,654. The flat washer thereby serves for distributing the compressive force of the nut to the underneath layer or object and the disc-spring serves for ensuring a defined compressive force even in case of substantial lengthening of the bolt due to thermal expansion or seatings in the bus bar. Even though such an assembly of the nut, the disc-spring, and the flat washer fulfils its intended purpose, it is complicated and time-consuming for mounting, since the parts must be arranged in the right order and direction before being fastened. In addition, care must be taken to assemble the nut with the appropriate washers in terms of size and material. In particular, if the nuts are mounted to places which are difficult to access, this assembly of the nut and the washers is prone to errors. The components of the assembly could drop off in the course of being mounted and thereby lead to damages or short-circuits, in particular in bus bar installations.